Neutorphil aggregation is a multistep process involving integrins and L-selectin. We are using flow cytometry o define a counterstructure for L-selectin in neutrophil aggregation. We have used A1 glycoprotease (Mellors) to demonstrate a role for O-glycosylated proteins in the aggregation process (Bennett et. al. J. Leuk. Biol, 1995) and characterized preparation of the glycoprotease. We have tentatively identified an O-glycosylated protein important to the process using antibodies (McEver and Moore). A manuscript has been submitted (Guyer, et. al, 1996)